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SPIR generator/Clang Installation Instructions

These instructions describe how to build, install and operate SPIR generator Clang.

Step 1: Organization

SPIR generator/Clang is designed to be built as part of an LLVM build.

SPIR generator/Clang is based on LLVM/Clang version 3.2.

The LLVM source code could be downloaded from

It is also available directly from the LLVM svn server:

  svn co llvm

Or could be cloned from LLVM git repository:

  git clone llvm
  cd llvm
  git checkout --track -b release_32 remotes/origin/release_32

Assuming that the LLVM source code is located at $LLVM_SRC_ROOT, then the clang source code should be installed as: $LLVM_SRC_ROOT/tools/clang.

The directory is not required to be called clang, but doing so will allow the LLVM build system to automatically recognize it and build it along with LLVM.

  cd $LLVM_SRC_ROOT/tools
  git clone clang
  cd clang
  git checkout --track -b spir_12 remotes/origin/spir_12

Step 2: Configure and Build LLVM

Configure and build your copy of LLVM (see $LLVM_SRC_ROOT/GettingStarted.html for more information).

Assuming you installed clang at $LLVM_SRC_ROOT/tools/clang then Clang will automatically be built with LLVM. Otherwise, run make in the Clang source directory to build Clang.

  • Note: currently there might be failures in check_clang project.

Step 3: (Optional) Verify Your Build

It is a good idea to run the Clang tests to make sure your build works correctly. From inside the Clang build directory, run make test to run the tests.

Step 4: Install Clang

If you wish to run Clang from the generated binary directory, you may skip this section.

From inside the Clang build directory, run make install to install the Clang compiler and header files into the prefix directory selected when LLVM was configured.

The Clang compiler is available as clang and clang++. It supports a gcc like command line interface. See the man page for clang (installed into $prefix/share/man/man1) for more information.

Step 5: Creating SPIR binaries

To create a SPIR binary from a valid OpenCL-C file (.cl), use the following command lines:

  clang -cc1 -emit-llvm-bc -triple <triple> <OpenCL compile options> -cl-spir-compile-options "<OpenCL compile options>" -include <opencl_spir.h> -o <output> <input>
  • <triple>: for 32 bit SPIR use spir-unknown-unknown, for 64 bit SPIR use spir64-unknown-unknown.
  • Note: <OpenCL compile options> appears twice. The command line option -cl-spir-compile-options "<OpenCL compile options>" specifies the compile options that occur in the SPIR metadata.
  • <opencl_spir.h>: download opencl_spir.h from
  • -O: -O0 (default) is the only tested option value at the moment. It's assumed by design that all optimizations are executed by SPIR consumer.

Reporting issues

Bugs/feature requests can be filed via github or Khronos Bugzilla bug tracker.